title: Immunological and viral determinants of dengue severity in hospitalized adults in Ha Noi, Viet Nam.
abstract: BACKGROUND
  The relationships between the infecting dengue serotype, primary and secondary infection, viremia and dengue severity remain unclear. This cross-sectional study examined these interactions in adult patients hospitalized with dengue in Ha Noi.
  
  
  RESULTS
  158 patients were enrolled between September 16 and November 11, 2008. Quantitative RT-PCR, serology and NS1 detection were used to confirm dengue infection, determine the serotype and plasma viral RNA concentration, and categorize infections as primary or secondary. 130 (82%) were laboratory confirmed. Serology was consistent with primary and secondary infection in 34% and 61%, respectively. The infecting serotype was DENV-1 in 42 (32%), DENV-2 in 39 (30%) and unknown in 49 (38%). Secondary infection was more common in DENV-2 infections (79%) compared to DENV-1 (36%, p<0.001). The proportion that developed dengue haemorrhagic fever (DHF) was 32% for secondary infection compared to 18% for primary infection (p = 0.14), and 26% for DENV-1 compared to 28% for DENV-2. The time until NS1 and plasma viral RNA were undetectable was shorter for DENV-2 compared to DENV-1 (p≤0.001) and plasma viral RNA concentration on day 5 was higher for DENV-1 (p = 0.03). Plasma viral RNA concentration was higher in secondary infection on day 5 of illness (p = 0.046). We didn't find an association between plasma viral RNA concentration and clinical severity.
  
  
  CONCLUSIONS
  Dengue is emerging as a major public health problem in Ha Noi. DENV-1 and DENV-2 were the prevalent serotypes with similar numbers and clinical presentation. Secondary infection may be more common amongst DENV-2 than DENV-1 infections because DENV-2 infections resulted in lower plasma viral RNA concentrations and viral RNA concentrations were higher in secondary infection. The drivers of dengue emergence in northern Viet Nam need to be elucidated and public health measures instituted.
authors.affiliation: Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Hanoi, Socialist Republic of Vietnam. afox@oucru.org
authors.forename: Annette
authors.initials: A
authors.lastname: Fox
authors.forename: Nguyen Minh Hoa
authors.initials: NM
authors.lastname: Le
authors.forename: Cameron P
authors.initials: CP
authors.lastname: Simmons
authors.forename: Marcel
authors.initials: M
authors.lastname: Wolbers
authors.forename: Heiman F L
authors.initials: HF
authors.lastname: Wertheim
authors.forename: Thi Khuong
authors.initials: TK
authors.lastname: Pham
authors.forename: Thi Hai Ninh
authors.initials: TH
authors.lastname: Tran
authors.forename: Thi Minh Lien
authors.initials: TM
authors.lastname: Trinh
authors.forename: Thi Lien
authors.initials: TL
authors.lastname: Nguyen
authors.forename: Vu Trung
authors.initials: VT
authors.lastname: Nguyen
authors.forename: Duc Hien
authors.initials: DH
authors.lastname: Nguyen
authors.forename: Jeremy
authors.initials: J
authors.lastname: Farrar
authors.forename: Peter
authors.initials: P
authors.lastname: Horby
authors.forename: Walter R
authors.initials: WR
authors.lastname: Taylor
authors.forename: Van Kinh
authors.initials: VK
authors.lastname: Nguyen
mesh_terms: D000328:Adult; D016000:Cluster Analysis; D003430:Cross-Sectional Studies; D003715:Dengue / Q000145:classification / Q000276:immunology* / Q000473:pathology* / Q000821:virology; D003716:Dengue Virus / Q000235:genetics / Q000276:immunology / Q000472:pathogenicity*; D005260:Female; D005838:Genotype; D006760:Hospitalization; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D012367:RNA, Viral / Q000097:blood / Q000235:genetics; D017422:Sequence Analysis, DNA; D012703:Serotyping; D012720:Severity of Illness Index; D014744:Vietnam; D019562:Viral Load
chemical_list: D012367:RNA, Viral